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Planner speedup hacking. Avoid saving useless pathkeys, so that path

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comparison does not consider paths different when they differ only in
uninteresting aspects of sort order.  (We had a special case of this
consideration for indexscans already, but generalize it to apply to
ordered join paths too.)  Be stricter about what is a canonical pathkey
to allow faster pathkey comparison.  Cache canonical pathkeys and
dispersion stats for left and right sides of a RestrictInfo's clause,
to avoid repeated computation.  Total speedup will depend on number of
tables in a query, but I see about 4x speedup of planning phase for
a sample seven-table query.
This commit is contained in:
Tom Lane
2000-12-14 22:30:45 +00:00
parent db11f4382a
commit ea166f1146
16 changed files with 622 additions and 365 deletions
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3
src/include/optimizer/pathnode.h
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@@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2000, PostgreSQL, Inc
* Portions Copyright (c) 1994, Regents of the University of California
*
* $Id: pathnode.h,v 1.31 2000/11/12 00:37:01 tgl Exp $
* $Id: pathnode.h,v 1.32 2000/12/14 22:30:45 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -30,6 +30,7 @@ extern Path *create_seqscan_path(RelOptInfo *rel);
extern IndexPath *create_index_path(Query *root, RelOptInfo *rel,
IndexOptInfo *index,
List *restriction_clauses,
List *pathkeys,
ScanDirection indexscandir);
extern TidPath *create_tidscan_path(RelOptInfo *rel, List *tideval);
extern AppendPath *create_append_path(RelOptInfo *rel, List *subpaths);